Generally, when it is intended to park a vehicle movement of the vehicle is restricted by actuating a parking brake.
As for such a parking brake, in general, an equalizer equally distributes force applied to parking cables pulled by a parking brake lever) to brakes mounted on wheels and thus the brakes restrict the wheels to prevent motion of the vehicle.
As described above, the parking brake was inconvenient for the drivers. Accordingly, an EPB (Electrical Parking Brake) generating parking clamping force through power of a motor by operating a button is adopted for improvement of convenience and product attractiveness.
Even though such an EPB has high installation flexibility for the vehicle, recently, the mountability of the EPB is further facilitated by adopting a method of integrating the EPB with a caliper serving as a braking device.
In a case when the EPB is integrated with the caliper, it is preferable that the EPB is formed in a compact size in which the size of the caliper to be mounted is increased by adopting a gear device for converting a final output into a large load while using a smaller motor.
However, even though the motor had to be downsized for such a characteristic, that is, overall downsizing of the EPB, the final output through gear transmission decreases in a case when the motor is small and thus clamping force (in general, 1,200 Kgf) for maintaining parking braking decreases, thereby lowering reliability for performance of the EPB.
The clamping force enough to maintain the parking braking is generated by increasing the power of the motor, the overall size of the EPB is increased due to the motor, thereby lowering the mountability.
As a result, it is focused on design of the gear device for converting the power of the motor so that the EPB having the sufficient final output and the compact size is designed even though the motor is downsized, but the gear device is constituted by a minimum configuration, for example, at least two-stage carrier, two-stage planetary gear, two sun gears, and a one input gear in order to achieve a gear ratio for forming a load serving sufficient clamping force. Therefore, a limit in miniaturization of the gear device may prevent the EPB from being mounted on the caliper due to a characteristic of the caliper mounted in a narrow space.